National Model Railroad Association
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The National Model Railroad Association, or NMRA, is a non-profit organization for those involved in the hobby or business of model railroading. It was founded in the United States in 1935, and is now active in Canada, Australia, Great Britain, and the Netherlands. It was previously headquartered in Indianapolis, Indiana, and is now based in Chattanooga, Tennessee.
The best-known activity of the NMRA is the defining of standards, and advisory documents known as Recommended Practices (RP), for model railroad equipment. Many standards defined by the NMRA are widely followed by the industry and modellers, including their HO scale track and wheel standards (S-3, S-4) and related RPs (RP2, 8, 10-15, and 25) and their Digital Command Control (DCC) standard set (S-9.1, S-9.2, and RP9.1.1 through RP9.3.2).
The RP25 wheel design in particular has been critical in ensuring the reliability and interoperability of US-prototype model railroad equipment, since practically every manufacturer of such equipment uses wheels conforming to the RP. This is in marked contrast to the British market, in which there is no accepted standard among manufacturers. In Europe, the NEM standard is widely followed, but this is generally further away from prototype accuracy than NMRA standards, and the NEM wheel design is particularly so. This results in interoperability restrictions between European and American wheels and trackwork.
The NMRA also considers the education of model railroaders and encouraging learning and improving modellers' skills to be part of its mission. The NMRA runs an achievement program to encourage these skills, and runs modelling contests.
Promotion of the model railroading hobby is also part of the NMRA's purpose.
The NMRA is home of the A.C. Kalmbach Memorial Library, which houses railroad-related books and videos, was recently designated as the official railroad library of the state of Tennessee. The library is adjacent to the Norfolk Southern Railway Georgia Division and the Tennessee Valley Railroad Museum. It is named for Al C. Kalmbach, founder of Kalmbach Publishing, whose original magazines are Model Railroader and Trains.
